[1256] Lymphoepithelial-Like Carcinoma of the Oropharynx: A Morphologic Variant of HPV-Related Head and Neck Carcinoma

AD Singhi, EB Stelow, SE Mills, WH Westra. The Johns Hopkins Medical Institutions, Baltimore, MD; University of Virginia, Charlottesville, VA

Background: Human papillomavirus-associated squamous cell cancer of the head and neck (HPV-HNSCC) represents an important subgroup of head and neck cancer that is characterized by distinct epidemiological, clinical and pathologic features including a relatively constant microscopic appearance. For those cancers that deviate from the morphologic prototype, an association with HPV may not be recognized and accurate tumor classification may not be achieved.
Design: We have identified 22 cases of HPV-HNSCC with well developed lymphoepithelial-like features including tumor cells with syncitial cytoplasm, vesicular nuclei and large central nucleoli dispersed in an inflammatory background as cell clusters or single cells. The pattern closely resembles Epstein Barr virus (EBV)-induced undifferentiated carcinoma of the nasopharynx. Indeed, 3 of the carcinomas presenting as lymph node metastases were originally misdiagnosed as metastatic nasopharyngeal carcinoma. These cases were analyzed for the presence of HPV and EBV using p16 immunohistochemistry and viral in-situ hybridization.
Results: Unlike nasopharyngeal carcinoma, the cases were of oropharyngeal origin, p16 positive by immunohistochemistry (22 of 22, 100%), HPV-16 positive by in-situ hybridization (19 of 22, 86%) and EBV negative by in-situ hybridization (21 of 21, 100%). Like conventional HPV-related HNSCC, the cases tended to occur in patients under 60 years of age (82%), men (71%), and non-smokers (88%).
Conclusions: For carcinomas of the head and neck that exhibit lymphoepithelial features, one cannot assume an EBV-driven process by morphology alone. HPV testing has disclosed a previously unrecognized morphologic variant of HPV-HNSCC that is microscopically indistinguishable from EBV-related nasopharyngeal carcinoma. For lymphoepithelial-like carcinomas presenting as cervical lymph node metastases, testing for HPV and EBV is mandatory.
Category: Head & Neck

Tuesday, March 23, 2010 1:00 PM

Poster Session IV # 159, Tuesday Afternoon

 

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